<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>4_react生命周期(新)</title>
</head>
<body>
    <div id="test"></div>
    <!-- 引入react核心库 -->
    <script crossorigin src="../17.0.1/react.development.js"></script>
    <!-- 引入react-dom，用于支持react操作DOM -->
    <script crossorigin src="../17.0.1/react-dom.development.js"></script>
    <!-- 引入babel，用于将jsx转为js -->
    <script type="text/javascript" src="https://unpkg.com/babel-standalone@6.26.0/babel.js"></script>
    <script type="text/javascript" src="https://unpkg.com/prop-types@15.6.2/prop-types.js"></script> 
    <script type="text/babel">
        
        //创建组件
        class Count extends React.Component {
    
            //构造器
            constructor(props) {
                console.log('Count---constructor');
                super(props)
                //初始化状态
                this.state = {count: 0}
            }
    
            //加1按钮的回调
            add = () => {
                //获取原状态
                const {count} = this.state
                //更新状态
                this.setState({count: count + 1})
            }
    
            //卸载组件按钮的回调
            death = () => {
                ReactDOM.unmountComponentAtNode(document.getElementById('test'))
            }
    
            //强制更新按钮的回调
            force = () => {
                this.forceUpdate()
            }
            //不咋用
            static getDerivedStateFromProps(props,state){
                console.log('count---getDerivedStateFromProps props==>',props)
                console.log('count---getDerivedStateFromProps state==>',state)

                return null
            }
    
            
    
            render() {
                    console.log('Count---render');
                    const {count} = this.state
                return (
                    <div>
                        <h2>当前求和为：{count}</h2>
                        <button onClick={this.add}>点我+1</button>
                        <button onClick={this.death}>卸载组件</button>
                        <button onClick={this.force}>不更改任何状态中的数据，强制更新一下</button>
                    </div>
                )
            }
            
            getSnapshotBeforeUpdate(){
                console.log('Count---getSnapshotBeforeUpdate');
                return this.state.count
            }

            //组件挂载完毕的钩子
            componentDidUpdate(preProps,preState,snapShotValue) {
                console.log('Count---componentDidUpdate',preProps,preState,snapShotValue);
            }

        }
    
        
    
        //渲染组件
        ReactDOM.render(<Count count={199}/>, document.getElementById('test'))
    </script>
        
</body>
</html>